This application claims priority of Korea patent Application No. 99-66740, filed on Dec. 30, 1999.
(a) Field of the Invention
The present invention relates to a parking mechanism for a vehicle equipped with an automatic transmission.
(b) Description of the Related Art
Typically, automatic transmissions for vehicles use planetary gear mechanisms or continuously variable gear mechanism as driving torque transmission means. Such an automatic transmission is selected and placed into any desired range, such as forward ranges, a reverse range, a neutral range and a parking range, by means of a shift lever manipulated by a driver. A selection of parking range causes a parking mechanism to lock a transmission shaft of the automatic transmission.
FIG. 6 schematically shows a conventional parking mechanism. This parking mechanism comprises a detent plate 100 rotated by operation of a shift lever (not shown), a push rod 102 operated by the detent plate 100, a cam 104 formed at one end of the push rod 102 so as to move in a rectilinear direction along a guide 106 by the push rod 102, a parking sprag 108 which is pivotally mounted to a transmission housing (not shown) and contacts the cam 104 at its one end, and an annulus gear 112 having teeth 114 that engage a tooth 110 formed at the other end of the parking sprag 108 to lock the transmission.
Once the shift lever is manipulated to be located at P range, the push rod 102 moves in a rectilinear direction such that the cam 104 pushes up a proximal end of the parking sprag 108 and pushes down a distal end of the parking sprag 108. Accordingly, the parking sprag 108 is engaged with the annulus gear 112, thereby locking the transmission.
As described above, the conventional parking mechanism requires a large number of parts, i.e., the parking sprag, the annulus gear, the push rod, and the cam, etc. Furthermore, the number of parts occupies a lot of space so mounting problems occur.
Also, it is likely that the parking sprag can become disengaged from the annulus gear by an exterior impact when the vehicle is parked on a steep slope.
The present invention has been made in an effort to solve the above problems of the prior art.
It is an object of the present invention to provide an improved parking mechanism capable of minimizing space occupancy as well as whole manufacturing costs by reducing parts and ensuring reliable parking operation even on a steep slope.
To achieve the above object, a parking mechanism for an automatic transmission of the present invention comprises a manual control shaft rotationally supported by a transmission housing, the manual control shaft cooperating with a shift lever, a detent plate mounted on the manual control shaft, an annulus gear formed on a transfer gear of the transmission, and a sprag interposed between the detent plate and the annulus gear, the sprag levering on a fulcrum shaft which is fixed to the transmission housing.